This invention relates to a water lock device for marine propulsion units and more particularly to an improved exhaust control valve for a marine propulsion unit for preventing the flow of water into the engine through the exhaust system.
As is well known in marine propulsion, the exhaust gases from the powering engine are frequently discharged to the atmosphere through the body of water in which the associated watercraft is operated. This means that the exhaust discharge from the exhaust system is, at least at times, submerged. Because of this, there is always a danger that water can enter the engine through the exhaust system. Of course, this can cause difficulties. There have been proposed, therefore, control valves that are provided in the exhaust system and which will close under conditions when the engine is not running so as to prevent water from entering the engine through its exhaust system. The valves that have been proposed to control the exhaust gases and prevent such reverse water flow have, however, given rise to certain problems. Specifically, the valves of the type previously used for this purpose have a tendency to maintain in a closed position even if the engine is still running so long as some water is backed up into the exhaust system as can occur during reverse operation or upon sudden deceleration. As a result, the failure of the exhaust gases to be able to escape can cause stalling of the engine and this is not at all desirable.
It is, therefore, a principal object of this invention to provide a water lock device for a marine propulsion unit wherein the flow of exhaust gases will not be impeded even though water may enter the exhaust system.
It is a further object of this invention to provide an improved water control valve that will preclude the flow of water into the engine even though the exhaust gases are permitted to flow from the engine through the exhaust system.
In accordance with valves that have been previously proposed to control the flow of exhaust gases and inhibit the flow of water into the engine through the exhaust system, the valves have, for the most part, been gravity operated and have been weighted to a closed position. As a result, the engine must achieve a certain back pressure in order for the control valve to be opened. This aggravates the problems as aforedescribed.
It is, therefore, a further object of this invention to provide an improved control valve for the exhaust gases of a marine propulsion device which will operate more efficiently and which will achieve its desired results.
It is a further object of this invention to provide an improved control valve for a marine propulsion unit exhaust system that will permit the free flow of exhaust gases while preventing the flow of any water to the engine through the exhaust system.